1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to enabling enhanced uplink operations in a CDMA system.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, orthogonal frequency division multiple access (OFDMA) systems, and high speed packet access (HSPA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal may communicate with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-signal-out or a multiple-in-multiple-out (MIMO) system digital rotator
A MIMO system employs multiple (NT) transmit antennas and multiple (NR) receive antennas for data transmission. A MIMO channel formed by the NT transmit and NR receive antennas may be decomposed into NS independent channels, which are also referred to as spatial channels, where NS≦min {NT, NR}. Each of the NS independent channels corresponds to a dimension. The MIMO system can provide improved performance (e.g., higher throughput and/or greater reliability) if the additional dimensionalities created by the multiple transmit and receive antennas are utilized.
Further, in a CDMA system, high data rates may be offered on both downlink and uplink. For example, high speed uplink packet access (HSUPA) was introduced in WCDMA Release 6 with the initial peak is 5.7 Mbps, based on QPSK modulation. The peak rate is increased in Release 7 to 11.4 Mbps with 16QAM modulation. For such high data rates, the receive signal-to-noise-plus-interference ratio (SINR) may be so high that the interference between multiple paths may no longer negligible. Certain operations, including power control, may be enhanced for optimal performance in this new operation region.
Thus, improved apparatus and methods for enhancing high data rate uplink operations in a cellular wireless communication system are desired.